In a current PON, management of an ONU (Optical Network Unit, optical network unit) is implemented by using an OLT (Optical Line Terminal, optical line terminal). In a live network, a typical manner is to manage the ONU on the OLT by using a layer 3 protocol, for example, to manage the ONU by using the Telnet or SNMP protocol based on layer 3. In this manner, if a layer 3 network is disconnected, the OLT cannot manage the ONU, software commissioning maintenance personnel need to go to a site to resolve a hosting problem, and maintenance costs are very high.